diff --git a/src/ContentfulBundle.php b/src/ContentfulBundle.php
index 481e599..23f6fcc 100644
--- a/src/ContentfulBundle.php
+++ b/src/ContentfulBundle.php
@@ -17,7 +17,7 @@
 
 class ContentfulBundle extends Bundle
 {
-    public function build(ContainerBuilder $container)
+    public function build(ContainerBuilder $container): void
     {
         $container->addCompilerPass(new ProfilerControllerPass());
     }